Workers in many industries may be subjected to sudden thermal flashes directly in front of them. Electrical workers, for example, may experience an electric arc of great thermal intensity. This is particularly damaging to female workers because their brassieres may ignite outright, or the fabric and underwire melt or burn, causing severe injury. The traditional market solution has been to require that female employees exposed to these types of danger wear a brassiere made of a flame resistant fabric. This solution had its problems for the employer because such brassieres are expensive and are often difficult to fit and procure. There are also problems for the female employee in that such brassieres are made from a fabric having flame resistant fibers, which fabric is heavier than the female employee's regular brassiere fabric, and is somewhat stiff, uncomfortable and cumbersome.
Rather than focusing on the brassiere, the present invention is directed to providing the necessary protection for the employee by using a double layer of fabric strategically located across the front of the shirt. The double layers of fabric are significantly more protective than a single layer.
The double fabric layer is applied only in the front panels of the shirt for reasons, including the following:                1. Accidents involving electric arcs in work situations generally occur while the affected employee is working with his or her hands on a given task, and therefore generally occur in front of the affected employee. Infrared energy is the primary heat energy from an electric arc. It travels in a straight line and generally does not affect the back of a garment.        2. Most employees wear arc-rated gloves that extend to the elbow and are often also wearing full rubber sleeves that start at the wrists and go to the top of the shoulder (held in place with a strap that buckles around the back of the shoulders). This leaves a zone from the chest to the abdomen where a flame resistant shirt is the primary means of protection. The rubber sleeves and gloves are generally worn over a long sleeve flame resistant shirt or jacket. The gloves and sleeves have ATPVs that range from 25-100 calories square centimeter. Accordingly, the shirt needs little protection in the sleeve area if gloves and rubber sleeves are being utilized. For this reason, the main purpose for long sleeves in this application is for comfort under the heavy rubber. Lighter materials are the best for this purpose. Since the invention limits shirt construction to a double layer on the front panels only, the sleeves of the invented design are comprised of a single layer of fabric. The resulting thinness of the sleeves allows greater dexterity and the single layer construction of both the sleeves and rear of the shirt allow the employee's rear shoulder and back to ventilate heat and reduce the risk associated with heat build-up.        3. Typical shirts have an ATPV between 4.2-5.6 calories square centimeter. The highest scoring shirts that are presently commercially available are made from a flame resistant fabric known as Indura Ultra Soft® weighing 7.0 ounce per square yard. This fabric is desirable because it has an ATPV of 8.2 calories per square centimeter. The main reason that shirts manufactured from this fabric are not the industry's only choice is because they are heavy and hot. Heavier clothing traps heat and can result in excessive perspiration, (which can conduct electricity) heat exhaustion, heat stroke or other serious medical conditions which can affect the employee's judgment and dexterity on the job.        
Construction of shirts with double layers of frontal shirt fabric yields greatly increased protection in the chest/abdomen area with greater breathe-ability and reduced heat retention. It provides the manufacturer the ability to use double layers of lighter material in the front panels and one light layer everywhere else, instead of using a heavier-weight flame resistant fabric to construct the entire shirt.
The present invention allows easier enforcement of flame resistant uniform policies, which can be problematic for the employer for both male and female employees. Is the female employee wearing a Nomex IIIA® brassiere or the male employee wearing a 100% cotton undershirt? The invention's double ply construction provides equal or better protection and will have a distinctive front insignia to allow an employer to readily determine that the employee is compliant with the employer's uniform requirements.
The benefits of this type of construction extend to numerous other applications and the present application is in no way intended to be limited solely to shirts for female employees, nor solely to the type of sewing construction utilized in the attached drawings as being the definitive means of construction. By way of example, the drawings illustrate a construction that includes the entire front panel, however because of cost or in an effort to further reduce heat retention, a customer might direct that the design be altered to utilize the double ply front panel construction above the belt line and a single ply construction on that part of the shirt that is to be tucked into the pants. Also, in some cases it may be desirable to provide double layers in other areas.